On my Toshiba laptop, Ubuntu does seem to be able to hard blocking/unblocking the wifi card.

I dual-boot with Windows 7 and usually I leave wifi on. However, yesterday I disabled wifi while using Windows and when I rebooted into Ubuntu, I couldn't unblock the wifi. I had to reboot into Windows to re-enable the wifi.

rfkill unblock all and rfkill block all do not work for the hardware switch. Fn + F8 toggles the soft block of the wifi, whereas on Windows it toggles the hardware switch.